1. Field of the Invention
This invention involves novel polymerizable monomers having pendent carboxylic acid groups and polymers prepared from those monomers. The monomers have the structure: ##STR2## wherein R.sup.1 is hydrogen or methyl and Z is a direct bond or is a divalent alkyl radical having 1 to about 20 carbon atoms. Preferred divalent alkyl radicals are methylene chains --(--CH.sub.2 --).sub.n -- wherein n is 1 to 20.
This invention also relates to acid-functional polymers obtained by polymerizing, under free radical addition polymerization conditions, (i) the unsaturated acid monomer of this invention; and (ii) optionally, at least one other unsaturated monomer copolymerizable with the unsaturated acid monomer. The acid-functional polymers can be neutralized to provide water-reducible polymers and/or they may be utilized as corrosion or scale inhibitors, thickeners, dispersants and as reactive agents and/or crosslinking agents for compounds having functional groups, such as epoxy, hydroxyl or amine groups, which are reactive with acid groups. The acid-functional polymers can, therefore, be utilized in a variety of materials such as plastics, fibers, adhesives, paper sizing, inks and, particularly, coating compositions.
This invention also relates to novel reactive compositions which utilize the acid-functional polymer in combination with one or more other materials which can react with acid groups. These reactive compositions can be reacted at room temperature or force dried at temperatures ranging up to about 350.degree. F. or higher if desired. When utilized as reactive crosslinking agents for coatings, the acid-functional polymers may be utilized in a variety of coating applications, including primers and topcoats as well as clearcoats and/or basecoats in clearcoat/basecoat compositions.
The reactive compositions typically involve the combination of the acid-functional polymer with an epoxy-functional compound. The reactive composition may, optionally, also incorporate an anhydride-functional compound and, optionally, also a hydroxyl-functional compound. All of these combinations can provide fast reacting, durable coatings which may minimize the toxicity problems which may be associated with other low temperature curing systems.
2. Description of the Prior Art
Unsaturated, polymerizable acids, such as maleic acid, acrylic acid, methacrylic acid and polymers or copolymers incorporating these materials are known in the art. By the selection of one or more of these acids, polymers may be tailored to provide a desired acid value, reactivity or other desired property. The prior art has not, however, taught polymers obtained by the polymerization of the novel styrene-based tricarboxylic acid monomers of this invention.
Coating compositions comprising reactive combinations of epoxy-containing compounds and compounds having acid functionality are known in the art. For example, U.S. Pat. No. 4,859,758 teaches an acid-functional cellulose ester based polymer which could be used in combination with a polyepoxide, and optionally, a polyanhydride and, optionally a hydroxy-functional compound. Similarly, coating compositions comprising cyclic anhydrides and hydroxy-functional compounds are also known in the art. The prior art has not, however, taught the novel acid-functional polymers of this invention nor has it taught coating compositions comprising these acid-functional polymers with epoxy-functional compounds and, optionally, anhydride-functional compounds, and, optionally, hydroxy-functional compounds to provide low temperature curing coatings having excellent durability and performance.